Compensatory contribution of retinal larger vessels to perfusion density in diabetics without retinopathy

Vessel and perfusion densities may decrease before diabetic retinopathy appears; it is unknown whether these changes affect the contribution of vessel density to perfusion density. This was a non-experimental, comparative, prospective, cross-sectional study in non-diabetic subjects (group 1) and diabetics without retinopathy (group 2). Vessel and perfusion densities in the superficial capillary plexus were compared between groups at the center, inner, and full regions and by field (superior, temporal, inferior, nasal) using optical coherence tomography angiography. Coefficients of determination (R2) between vessel and perfusion densities were calculated to find the contribution of larger retinal vessels to perfusion density. Percent differences were used to evaluate the contribution of these vessels to perfusion density in a regression model. There were 62 participants, 31 eyes by group; vessel and perfusion densities as well as the coefficients of determination between them were lower in group 2, especially in the nasal field (R2 0.85 vs. 0.71), which showed a higher contribution of larger retinal vessels to perfusion density. The regression model adjusted to a quadratic equation. In diabetics without retinopathy the contribution of vessel density to perfusion density may decrease; a low vessel density may increase the contribution of larger retinal vessels to perfusion density.

Microvascular differences in amblyopic subgroups: An observational case–control study

Purpose To determine retinal microvascular differences among amblyopic subgroups and compare them with control eyes. Study Design This study was designed as an observational case–control study. Methods Twenty-three strabismic, 23 anisometropic, 22 meridional, 22 ametropic amblyopic eyes, and 24 healthy control eyes were included. The mean vessel densities in the deep and superficial capillary plexus, the foveal avascular zone area, the choriocapillaris flow area, and the foveal thickness were compared. Results Vessel density was markedly lower in all sectors of the amblyopic subgroups in the deep capillary plexus than in control eyes. Density was significantly lower in the superficial capillary plexus only in ametropic and meridional amblyopic eyes. Among these groups, the meridional amblyopic eyes had the largest choriocapillaris flow area ( p = 0.013) and the lowest vessel density in all sectors ( p < 0.001). The foveal avascular zone area was similar in all groups ( p = 0.561). The fovea was significantly thicker only in the anisometropic and meridional subgroups than control eyes ( p = 0.011, p = 0.001, respectively). The foveal avascular zone area was inversely related to the foveal thickness in all groups. Conclusion Retinal structural and microvascular differences were found among amblyopic subgroups. Optical coherence tomography angiography can noninvasively detect these variations, which may be related to the etiologic factors.

Differentiating features of OCT angiography in diabetic macular edema

The purpose of current study was to evaluate different optical coherence tomography angiography (OCTA) metrics in eyes with diabetic retinopathy with and without diabetic macular edema (DME). In this retrospective study, macular OCTA images of eyes with non-proliferative or proliferative diabetic retinopathy were evaluated. Vascular density, vascular complexity and non-perfusion densities were compared between eyes with and without DME. One-hundred-thirty-eight eyes of 92 diabetic patients including 49 eyes with DME were included. In multivariate analysis, the presence of DME was positively associated with geometric perfusion deficit (GPD) in superficial capillary plexus (SCP), capillary non-perfusion (CNP) of SCP, and GPD in deep capillary plexus (DCP) (all P < 0.05). In eyes with DME, central foveal thickness was associated with VD ratio (SCP/DCP) (P = 0.001) and FAZ area (P = 0.001). In conclusion, in eyes with diabetic retinopathy, the presence of DME was associated with more extensive capillary non-perfusion compared to those with no macular edema.

The relationship between carotid intima-media thickness and microvascular changes in retinal zones and optic disc in patients with type 1 diabetes mellitus

Purpose The aim of this study was to detect early retinal vascular changes with optical coherence tomography angiography (OCTA) in type 1 diabetes mellitus (T1DM) patients without diabetic retinopathy and to evaluate the correlation of the results with carotid intima-media thickness (IMT). Design This is a case–control and cross-sectional study. Methods This study included 38 adult patients with T1DM, and 38 age and gender-matched healthy controls. Retinal and optic disc (OD) measurements were taken using OCTA. The carotid artery IMT of each patient was measured using Doppler ultrasonography. Superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density, foveal avascular zone (FAZ), non-flow area (NFA) and foveal density (FD) were analysed in the fovea centred 6 × 6 mm macular area. The superficial capillary plexus and DCP were also scanned centred on the peripapillary region. The correlations between OCTA measurements and carotid IMT, duration of DM and haemoglobin A1c levels in patients with T1DM were evaluated. Results The mean values for carotid IMT were significantly higher in diabetic patients than in controls ( p < 0.001). The mean values for vessel density SCP, DCP and OD were significantly lower in the diabetic group ( p < 0.05). There were correlations between the carotid IMT and duration of T1DM and the evaluated parameters of OCTA. Conclusion Microvascular changes in the SCP and DCP in patients with T1DM without DR offer important data. OCTA can be used to detect early microvascular changes in patients with T1DM without DR. In addition, a relationship was found between SCP vascular dropout and carotid IMT.

Association of Microvasculature and Macular Sensitivity in Idiopathic Macular Epiretinal Membrane: Using OCT Angiography and Microperimetry

Purpose: To investigate the correlation between retinal capillary structure and macular function in patients with idiopathic epiretinal membrane (iERM) by using optical coherence tomography angiography (OCTA) and microperimetry.Methods: This retrospective and observational study included 30 idiopathic ERM eyes of 30 consecutive patients. OCTA was performed to evaluate macular microvasculature including the superficial capillary plexus, deep capillary plexus, and foveal avascular zone. Best corrected visual acuity (BCVA) and microperimetry were measured at baseline and 3 months after surgery. Associations between macular microvasculature and visual function were assessed.Results: Visual function including BCVA and macular sensitivity improved significantly at 3 months post-operatively (p &lt; 0.001). At baseline, BCVA was positively correlated with foveal or parafoveal sensitivities and negatively correlated with central foveal thickness (p &lt; 0.05). Pre-operative foveal sensitivity was significantly correlated with the vessel density of foveal or parafoveal superficial capillary plexus (p &lt; 0.05). A multiple regression model revealed that pre-operative vessel density of foveal deep capillary plexus was an independent positive prognostic factor for post-operative BCVA (B = −0.020 ± 0.006, p = 0.006) and macular sensitivity (B = 0.200 ± 0.081, p = 0.027).Conclusion: Integrated evaluation of iERM by using OCTA and microperimetry shows an association between microvasculature and macular sensitivity. Pre-operative vessel density of foveal deep capillary plexus assessed by OCTA may be a potentially valuable prognostic factor for iERM surgery.

OCTA in macular intraretinal microvascular abnormalities: Retinal vascular density remodeling after panretinal photocoagulation

Purpose To describe a case of macular intraretinal microvascular abnormality (IRMA) detected with Optical Coherence Tomography Angiography (OCTA) and to show its remodeling and vascular density changes after panretinal photocoagulation (PRP) during an 18-month follow-up. Methods Case report. Results A 22-year-old female patient with proliferative diabetic retinopathy was found to have a small hyperreflective formation with posterior shadow cone and signal flow, located at the temporal margin of the fovea avascular zone (FAZ), identified as macular IRMA with OCTA. Her best-corrected-visual acuity was 20/20. Four months later the macular IRMA was larger and, in its context, there was also an increase in the flow area in B-scan. The patient underwent PRP and after 18 months we observed a regression of macular IRMA and an increase in the superficial capillary plexus vessel density in all sectors in comparison to baseline. Conclusion OCTA is a non-invasive tool that recognize macular IRMA in diabetic retinopathy patient and it could be helpful to follow their qualitative and quantitative vascular evolution over time.

Evaluation of the Effect of Covid-19 on Optic Disk and Macula with Oct and Oct-Angiography

PURPOSE: The aim of this study was to investigate changes in the optic nerve, retina, and retinal vessel parameters in recovered COVID-19 patients and compare to the healthy subjects by using optical coherence tomography (OCT), optical coherence tomography angiography (OCT-A).METHODS: Fiftysix eyes of 29 patients recovered from COVID-19 infection and 47 eyes of 26 healthy subjects were enrolled in this study. COVID-19 patients had to be fully recovered and were evaluated 1-3 months after COVID-19 infection. The primary outcome resulted from OCTA studies of the following vascular structures: vessel density (VD) in the foveal superficial capillary plexus (SFVD), foveal deep capillary plexus (DFVD), parafoveal superficial capillary plexus (SPVD), parafoveal deep capillary plexus (SPVD), radial peripapillary capillaries (RPC), whole disc (WD), inside disc (InD), superior,inferior, nasal, temporal peripapillary retinal VD and foveal avascular zone (FAZ) compared to those of controls. Structural spectral domain (SD)-OCT parameters were also evaluated, foveal macular thickness (FMT), parafoveal macular thickness (PMT), choroidal thickness (CT) and retinal nerve fiber layer (RNFL).RESULTS: The patients showed a significant reduction in SPVD compared to those in healthy subjects (P=0.008). COVID-19 patients featured an increased CT compared to that in controls (P <0.001). No differences were found in the FMT or PMT between the groups. VD of WD was not significantly different between the groups but InD VD was reduced in patient group (p=0.027). The superior RNFL was increased in the COVID-19 group compared to that in controls (p=0.022).CONCLUSION: The eye is among the organs affected in COVID-19 infection. OCT and OCTA is a valuable non-invasive method that can be used to monitor the effects of COVID-19 on the retina, choroid and optic disc.

Effect of axial length on peripapillary microvasculature: An optical coherence tomography angiography study

Objective To investigate the effects of axial length (AL) on the peripapillary microvascular density acquired from optical coherence tomography angiography (OCTA). Methods Retrospective observational study. A total of 111 eyes from 111 normal healthy subjects were examined. The subjects were divided into three groups according to the AL: Group 1 (AL: < 24.0 mm; 35 eyes), Group 2 (AL: 24.0–25.99 mm; 37 eyes), and Group 3 (AL: ≥ 26 mm; 39 eyes). Peripapillary OCTA images were acquired using 6× 6 mm angiography scans, and vessel density (VD) and perfusion density (PD) of the superficial capillary plexus were calculated automatically. VD and PD were compared among the three groups according to the distance from the optic disc (inner and outer rings). Linear regression analyses were also performed to identify clinical factors associated with average VD. Results The average ALs of Groups 1–3 were 23.33± 0.57, 25.05± 0.60, and 27.42± 0.82, respectively. Average VD (P = 0.009) and PD (P = 0.029) in the inner ring increased with increasing AL. However, average VD (P < 0.001) and PD (P < 0.001) in the outer ring decreased with AL increased; the same trends were found for the full areas (VD, p<0.001; PD, p = 0.001). Average VDs in the inner and outer rings were not associated (P = 0.938). Conclusions Peripapillary VD and PD were significantly associated with AL. Depending on the distance from the disc, peripapillary VDs and PDs of the inner and outer rings were differentially affected by AL. Physicians should therefore consider the effects of AL in the analyses of peripapillary microvasculature.

Progressive macular ischemia in retinal vasculopathy with cerebral leukodystrophy

Purpose: We present a case of retinal vasculopathy with cerebral leukodystrophy and review the usefulness of optical coherence tomography angiography (OCT-A) in the assessment of long-term outcomes. Case description: A 31-year-old woman developed sudden-onset scotoma in her right eye. Fundus examination and fluorescein angiography showed a patch of soft exudate and capillary nonperfusion in the posterior pole and outside the vascular arcades. OCT-A revealed that the initial vessel density (VD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) of the right eye were 32% and 49.2%, respectively. Interestingly, over time, the VD of the SCP and DCP gradually decreased to 23.1% and 26.2%, respectively. In contrast, the initial VD of the SCP and DCP of the left eye were both stable at 44.3% and 56.2%, respectively, and only decreased slightly to 39.3% and 45.7%, respectively, over time. The average VD loss of the SCP and DCP, assessed over 1 year, was 8% and 13%, respectively, in the right eye, and 3% and 6%, respectively, in the left eye. Conclusion: Based on this case report, in which we demonstrated a long-term decline in VD of the macula in a young woman with mild retinal vasculopathy with cerebral leukodystrophy, we suggest that there is a potential and valuable role for OCT-A in this rare disease.

A comparative study of type 1 neovascularization: Neovascular age-related macular degeneration versus pachychoroid neovasculopathy

Purpose: This study aimed to compare type 1 choroidal neovascularization (CNV) characteristics in eyes with pachychoroid neovasculopathy (PNV) and neovascular age-related macular degeneration (nAMD) using optical coherence tomography angiography (OCTA). Methods: Treatment naive 23 eyes of 23 patients with PNV and 24 eyes of 24 patients with nAMD were evaluated. The height of pigment epithelial detachment (PED) and the central macular thickness were determined. OCTA sensitivity, CNV area, morphological patterns, and retinal superficial capillary plexus vessel density (SCP-VD) values were compared. The frequency of quiescent CNV, subretinal hyperreflective exudation (SHE), subretinal/intraretinal fluid, serous PED, double-layer sign (DLS), and pachyvessels were noted. Results: CNV was detected on OCTA in 83.3% of nAMD eyes and 91.3% of PNV eyes ( p = 0.66). Indistinct pattern was more common (74% vs 50%) and the CNV area (mm2) was smaller in PNV (0.77 ± 0.54 vs 1.57 ± 1.43) but did not reach significant levels ( p = 0.27 and 0.33 respectively). SCP-VD was similar between the groups ( p = 0.38). Statistically significant differences were found between groups in age and subfoveal choroidal thickness ( p < 0.05). DLS and pachyvessels were found to be more frequently in PNV ( p < 0.05). However, both groups had similar rates of quiescent CNV, SHE, subretinal/intraretinal fluid, and serous PED ( p > 0.05). Conclusion: Morphological features, area, and activation findings of type 1 CNV may play a limited role in differentiating nAMD and PNV cases.